The appearance of the third man was as disconcerting as it was mystifying. That he was sleuthing the other two was clear from the stealthy manner of his approach and the care he displayed in taking advantage of every scrap of shelter. He was an adept at the work. More than once the men looked round to make sure they were not followed; and each time, as if by instinct, the other had gone to cover.
As they reached the warehouse the couple became even more cautious, and the spy did not venture to show so much as the tip of his nose. With a last look round, they opened the door quickly and disappeared into the building.
I dared not show myself, of course, until I knew what the spy would do; and I felt extremely uncomfortable as I waited.
It was some minutes before he ventured any nearer; and then he came down the lane with cat-like stealth and absolutely noiseless tread, and at first did what I had done, listened intently for any sounds within the warehouse.
Presently he stepped back a pace and scrutinized the front, and then turned his attention to the adjoining building. While doing this, he came right up to the rubbish heap behind which I lay; and a few seconds later began to glance about him as if for a place in which to hide.
The heap appeared to suggest itself to him in the same light as it had to me; and I saw that discovery was inevitable.
I scrambled to my feet, therefore, not willing to be taken at a disadvantage; and without a sound he turned on the instant and bolted up the lane.
I was completely mystified by this sudden flight. He was a spy, of course; but whether he had been set on by the police, or was shadowing some suspected members of the band, I had no means of even guessing.
Nor had I the time. If he was from the police he would soon be back with help; while if he was one of the men, he would carry the news to his friends that some one else was dangerously interested in the proceedings.
It was clear that something was going on inside the place, and I had to find the means of ascertaining whether Althea's father was there.